1. Field of the Invention
The present invention generally relates to a fluid-dispensing pump for discharging a fluid stored inside a fluid-storing portion from a nozzle head by pressing the nozzle head.
2. Description of the Related Art
As this kind of fluid-dispensing pump, for example, a fluid-dispensing pump comprising a nozzle head for discharging a fluid, a fluid-storing portion for storing the liquid, a cylinder disposed on the upper side of the fluid-storing portion, a piston which can reciprocate inside the cylinder with the nozzle head being pressed, an inflow valve mechanism for letting the fluid stored in the fluid-storing portion flow into the cylinder with the piston being ascending, and an outflow valve mechanism for letting the fluid flow out to the nozzle head with the piston being descending has been used.
Particularly, after the cylinder is sent down by pressing the nozzle head and then a pressure applied to the nozzle head is removed, a metal coil spring used as a means of giving momentum sends a cylinder up again, and Japanese Patent Laid-open No. 2002-66401 discloses a fluid-dispensing pump having a configuration of maintaining it clean by preventing the coil spring from corroding.
The fluid-dispensing pump described in Japanese Patent Laid-open No. 2002-66401 comprises a piston which can reciprocate inside the cylinder, hollow first and second coupling tubes for sending the piston down by transmitting a pressure applied to the nozzle head by coupling the nozzle head and the piston, a coil spring disposed in the outer periphery of the first and second coupling tubes for giving momentum to the piston in a direction of sending it up, a first valve mechanism for letting a fluid stored in a fluid-storing portion flow into the cylinder with the piston being ascending, and a second valve mechanism for letting a fluid having flowed into the cylinder flow out to the nozzle head via inside the first and second coupling tubes with the piston being descending.
However, the fluid-dispensing pump described in Japanese Patent Laid-open No. 2002-66401 has the configuration in which a flow path leading into the first and the second coupling tubes from inside the cylinder is formed with the first and the second coupling tubes descending relative to the piston. Therefore, in order to prevent a fluid from leaking out to inside the first and the second coupling tubes by completely closing the flow path leading into the first and the second coupling tubes from inside the cylinder, this fluid-dispensing pump has a problem in that high machining accuracy is required for manufacturing the first and the second coupling tubes.